Community structure of Archaea in anaerobic granular sludge-suspended carrier biofilm reactor for 2, 4-dichlorophenol degradation

Archaea community structure in anaerobic granular sludge-suspended carrier biofilm reactor (ASBR) for 2,4-dichlorophenol degradation(2,4-DCP) was analyzed by 16S rDNA-based techniques. Total DNA were extracted directly from the top, middle and bottom layers of sludge in the ASBR and then amplified by polymerase chain reaction (PCR) with Archaea specific primer ARC21F/ARC958R. The positive PCR products were cloned and sequenced. The sequence analysis showed that there existed common Archaea in each layer of sludge in the ASBR and inoculated sludge, including Methanothrix soehngenii and uncultured archaeon. The abundance of M. soehngenii, uncultured archaeon TA05 and uncultured archaeon TA04 increased in the order; the inoculated sludge < the top < the middle < the bottom in the ASBR. However, the abundance of uncultured archaeon 44A-1 , uncultured archaeon 39-2 , uncultured archaeon 46-1 and uncultured archaeon 69-1 declined in the order; the inoculated sludge > the top > the middle > the bottom layer sludge in the ASBR. Some special Archaea were found, such as unidentified crenarchaeote in the top layer sludge and uncultured archaeon ZAR106 in the bottom layer sludge of the ASBR. Six Archaea originally existing in the inoculated sludge disappeared and the diversity of Archaea in the ASBR sludge decreased after 2,4-DCP-acclimation. The abundance of Archaea changed markedly in the bottom layer sludge of the ASBR.